/*
** $Id: lua.c,v 1.230 2017/01/12 17:14:26 roberto Exp $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/

#define lua_c

#include "lprefix.h"

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#if !defined(LUA_PROMPT)
#define LUA_PROMPT      "> "
#define LUA_PROMPT2     ">> "
#endif

#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME        "lua"
#endif

#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT        512
#endif

#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR        "LUA_INIT"
#endif

#define LUA_INITVARVERSION  LUA_INIT_VAR LUA_VERSUFFIX


/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if !defined(lua_stdin_is_tty)  /* { */

#if defined(LUA_USE_POSIX)  /* { */

#include <unistd.h>
#define lua_stdin_is_tty()  isatty(0)

#elif defined(LUA_USE_WINDOWS)  /* }{ */

#include <io.h>
#include <windows.h>

#define lua_stdin_is_tty()  _isatty(_fileno(stdin))

#else               /* }{ */

/* ISO C definition */
#define lua_stdin_is_tty()  1  /* assume stdin is a tty */

#endif              /* } */

#endif              /* } */


/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if !defined(lua_readline)  /* { */

#if defined(LUA_USE_READLINE)   /* { */

#include <readline/readline.h>
#include <readline/history.h>
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,line)    ((void)L, add_history(line))
#define lua_freeline(L,b)   ((void)L, free(b))

#else               /* }{ */

#define lua_readline(L,b,p) \
        ((void)L, fputs(p, stdout), fflush(stdout),  /* show prompt */ \
        fgets(b, LUA_MAXINPUT, stdin) != NULL)  /* get line */
#define lua_saveline(L,line)    { (void)L; (void)line; }
#define lua_freeline(L,b)   { (void)L; (void)b; }

#endif              /* } */

#endif              /* } */

/* 这里待优化不要去修改源码, 所有动作都在luaconf.h和lua2rtt.c和lua2rtt.h中添加,
 * 目前保存历史记录不是通过lua_saveline实现, 评估使用lua_saveline方法是否更加
 * 方便通用和简单????? */
#undef lua_readline
#undef lua_saveline
#undef lua_freeline

extern int lua2rtt_readline(const char *prompt, char *buffer, int length);
#define lua_readline(L,b,p)     (lua2rtt_readline(p, b, LUA_MAXINPUT))
#define lua_saveline(L,idx)     { (void)L; (void)idx; }
#define lua_freeline(L,b)       { (void)L; (void)b; }

static lua_State *globalL = NULL;

static const char *progname = LUA_PROGNAME;


/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop(lua_State *L, lua_Debug *ar)
{
    (void)ar;  /* unused arg. */
    lua_sethook(L, NULL, 0, 0);  /* reset hook */
    luaL_error(L, "interrupted!");
}


/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction(int i)
{
    signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
    lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}


static void print_usage(const char *badoption)
{
    lua_writestringerror("%s: ", progname);
    if (badoption[1] == 'e' || badoption[1] == 'l')
        lua_writestringerror("'%s' needs argument\n", badoption);
    else
        lua_writestringerror("unrecognized option '%s'\n", badoption);
    lua_writestringerror(
        "usage: %s [options] [script [args]]\n"
        "Available options are:\n"
        "  -e stat  execute string 'stat'\n"
        "  -i       enter interactive mode after executing 'script'\n"
        "  -l name  require library 'name'\n"
        "  -v       show version information\n"
        "  -E       ignore environment variables\n"
        "  --       stop handling options\n"
        "  -        stop handling options and execute stdin\n"
        ,
        progname);
}


/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message(const char *pname, const char *msg)
{
    if (pname) lua_writestringerror("%s: ", pname);
    lua_writestringerror("%s\n", msg);
}


/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report(lua_State *L, int status)
{
    if (status != LUA_OK)
    {
        const char *msg = lua_tostring(L, -1);
        l_message(progname, msg);
        lua_pop(L, 1);  /* remove message */
    }
    return status;
}


/*
** Message handler used to run all chunks
*/
static int msghandler(lua_State *L)
{
    const char *msg = lua_tostring(L, 1);
    if (msg == NULL)    /* is error object not a string? */
    {
        if (luaL_callmeta(L, 1, "__tostring") &&  /* does it have a metamethod */
                lua_type(L, -1) == LUA_TSTRING)  /* that produces a string? */
            return 1;  /* that is the message */
        else
            msg = lua_pushfstring(L, "(error object is a %s value)",
                                  luaL_typename(L, 1));
    }
    luaL_traceback(L, L, msg, 1);  /* append a standard traceback */
    return 1;  /* return the traceback */
}


/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall(lua_State *L, int narg, int nres)
{
    int status;
    int base = lua_gettop(L) - narg;  /* function index */
    lua_pushcfunction(L, msghandler);  /* push message handler */
    lua_insert(L, base);  /* put it under function and args */
    globalL = L;  /* to be available to 'laction' */
    signal(SIGINT, laction);  /* set C-signal handler */
    status = lua_pcall(L, narg, nres, base);
    signal(SIGINT, SIG_DFL); /* reset C-signal handler */
    lua_remove(L, base);  /* remove message handler from the stack */
    return status;
}


static void print_version(void)
{
    lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
    lua_writeline();
}


/*
** Create the 'arg' table, which stores all arguments from the
** command line ('argv'). It should be aligned so that, at index 0,
** it has 'argv[script]', which is the script name. The arguments
** to the script (everything after 'script') go to positive indices;
** other arguments (before the script name) go to negative indices.
** If there is no script name, assume interpreter's name as base.
*/
static void createargtable(lua_State *L, char **argv, int argc, int script)
{
    int i, narg;
    if (script == argc) script = 0;  /* no script name? */
    narg = argc - (script + 1);  /* number of positive indices */
    lua_createtable(L, narg, script + 1);
    for (i = 0; i < argc; i++)
    {
        lua_pushstring(L, argv[i]);
        lua_rawseti(L, -2, i - script);
    }
    lua_setglobal(L, "arg");
}


static int dochunk(lua_State *L, int status)
{
    if (status == LUA_OK) status = docall(L, 0, 0);
    return report(L, status);
}


static int dofile(lua_State *L, const char *name)
{
    return dochunk(L, luaL_loadfile(L, name));
}


static int dostring(lua_State *L, const char *s, const char *name)
{
    return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
}


/*
** Calls 'require(name)' and stores the result in a global variable
** with the given name.
*/
static int dolibrary(lua_State *L, const char *name)
{
    int status;
    lua_getglobal(L, "require");
    lua_pushstring(L, name);
    status = docall(L, 1, 1);  /* call 'require(name)' */
    if (status == LUA_OK)
        lua_setglobal(L, name);  /* global[name] = require return */
    return report(L, status);
}


/*
** Returns the string to be used as a prompt by the interpreter.
*/
static const char *get_prompt(lua_State *L, int firstline)
{
    const char *p;
    lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
    p = lua_tostring(L, -1);
    if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
    return p;
}

/* mark in error messages for incomplete statements */
#define EOFMARK     "<eof>"
#define marklen     (sizeof(EOFMARK)/sizeof(char) - 1)


/*
** Check whether 'status' signals a syntax error and the error
** message at the top of the stack ends with the above mark for
** incomplete statements.
*/
static int incomplete(lua_State *L, int status)
{
    if (status == LUA_ERRSYNTAX)
    {
        size_t lmsg;
        const char *msg = lua_tolstring(L, -1, &lmsg);
        if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)
        {
            lua_pop(L, 1);
            return 1;
        }
    }
    return 0;  /* else... */
}


/*
** Prompt the user, read a line, and push it into the Lua stack.
*/
static int pushline(lua_State *L, int firstline)
{
    char buffer[LUA_MAXINPUT];
    char *b = buffer;
    size_t l;
    const char *prmt = get_prompt(L, firstline);
    int readstatus = lua_readline(L, b, prmt);
    if (readstatus == 0)
        return 0;  /* no input (prompt will be popped by caller) */
    lua_pop(L, 1);  /* remove prompt */
    l = strlen(b);
    if (l > 0 && b[l - 1] == '\n') /* line ends with newline? */
        b[--l] = '\0';  /* remove it */
    if (firstline && b[0] == '=')  /* for compatibility with 5.2, ... */
        lua_pushfstring(L, "return %s", b + 1);  /* change '=' to 'return' */
    else
        lua_pushlstring(L, b, l);
    lua_freeline(L, b);
    return 1;
}


/*
** Try to compile line on the stack as 'return <line>;'; on return, stack
** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn(lua_State *L)
{
    const char *line = lua_tostring(L, -1);  /* original line */
    const char *retline = lua_pushfstring(L, "return %s;", line);
    int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
    if (status == LUA_OK)
    {
        lua_remove(L, -2);  /* remove modified line */
        if (line[0] != '\0')  /* non empty? */
            lua_saveline(L, line);  /* keep history */
    }
    else
        lua_pop(L, 2);  /* pop result from 'luaL_loadbuffer' and modified line */
    return status;
}


/*
** Read multiple lines until a complete Lua statement
*/
static int multiline(lua_State *L)
{
    for (;;)    /* repeat until gets a complete statement */
    {
        size_t len;
        const char *line = lua_tolstring(L, 1, &len);  /* get what it has */
        int status = luaL_loadbuffer(L, line, len, "=stdin");  /* try it */
        if (!incomplete(L, status) || !pushline(L, 0))
        {
            lua_saveline(L, line);  /* keep history */
            return status;  /* cannot or should not try to add continuation line */
        }
        lua_pushliteral(L, "\n");  /* add newline... */
        lua_insert(L, -2);  /* ...between the two lines */
        lua_concat(L, 3);  /* join them */
    }
}


/*
** Read a line and try to load (compile) it first as an expression (by
** adding "return " in front of it) and second as a statement. Return
** the final status of load/call with the resulting function (if any)
** in the top of the stack.
*/
static int loadline(lua_State *L)
{
    int status;
    lua_settop(L, 0);
    if (!pushline(L, 1))
        return -1;  /* no input */
    if ((status = addreturn(L)) != LUA_OK)  /* 'return ...' did not work? */
        status = multiline(L);  /* try as command, maybe with continuation lines */
    lua_remove(L, 1);  /* remove line from the stack */
    lua_assert(lua_gettop(L) == 1);
    return status;
}


/*
** Prints (calling the Lua 'print' function) any values on the stack
*/
static void l_print(lua_State *L)
{
    int n = lua_gettop(L);
    if (n > 0)    /* any result to be printed? */
    {
        luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
        lua_getglobal(L, "print");
        lua_insert(L, 1);
        if (lua_pcall(L, n, 0, 0) != LUA_OK)
            l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
                                                lua_tostring(L, -1)));
    }
}

/*
** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
** print any results.
*/
static void doREPL(lua_State *L)
{
    int status;
    const char *oldprogname = progname;
    progname = NULL;  /* no 'progname' on errors in interactive mode */
    while ((status = loadline(L)) != -1)
    {
        if (status == LUA_OK)
            status = docall(L, 0, LUA_MULTRET);
        if (status == LUA_OK) l_print(L);
        else report(L, status);
    }
    lua_settop(L, 0);  /* clear stack */
    lua_writeline();
    progname = oldprogname;
}

/*
** Push on the stack the contents of table 'arg' from 1 to #arg
*/
static int pushargs(lua_State *L)
{
    int i, n;
    if (lua_getglobal(L, "arg") != LUA_TTABLE)
        luaL_error(L, "'arg' is not a table");
    n = (int)luaL_len(L, -1);
    luaL_checkstack(L, n + 3, "too many arguments to script");
    for (i = 1; i <= n; i++)
        lua_rawgeti(L, -i, i);
    lua_remove(L, -i);  /* remove table from the stack */
    return n;
}

static int handle_script(lua_State *L, char **argv)
{
    int status;
    const char *fname = argv[0];
    if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
        fname = NULL;  /* stdin */
    status = luaL_loadfile(L, fname);
    if (status == LUA_OK)
    {
        int n = pushargs(L);  /* push arguments to script */
        status = docall(L, n, LUA_MULTRET);
    }
    return report(L, status);
}

/* bits of various argument indicators in 'args' */
#define has_error   1   /* bad option */
#define has_i       2   /* -i */
#define has_v       4   /* -v */
#define has_e       8   /* -e */
#define has_E       16  /* -E */

/*
** Traverses all arguments from 'argv', returning a mask with those
** needed before running any Lua code (or an error code if it finds
** any invalid argument). 'first' returns the first not-handled argument
** (either the script name or a bad argument in case of error).
*/
static int collectargs(char **argv, int *first)
{
    int args = 0;
    int i;
    for (i = 1; argv[i] != NULL; i++)
    {
        *first = i;
        if (argv[i][0] != '-')  /* not an option? */
            return args;  /* stop handling options */
        switch (argv[i][1])    /* else check option */
        {
        case '-':  /* '--' */
            if (argv[i][2] != '\0')  /* extra characters after '--'? */
                return has_error;  /* invalid option */
            *first = i + 1;
            return args;
        case '\0':  /* '-' */
            return args;  /* script "name" is '-' */
        case 'E':
            if (argv[i][2] != '\0')  /* extra characters after 1st? */
                return has_error;  /* invalid option */
            args |= has_E;
            break;
        case 'i':
            args |= has_i;  /* (-i implies -v) *//* FALLTHROUGH */
        case 'v':
            if (argv[i][2] != '\0')  /* extra characters after 1st? */
                return has_error;  /* invalid option */
            args |= has_v;
            break;
        case 'e':
            args |= has_e;  /* FALLTHROUGH */
        case 'l':  /* both options need an argument */
            if (argv[i][2] == '\0')    /* no concatenated argument? */
            {
                i++;  /* try next 'argv' */
                if (argv[i] == NULL || argv[i][0] == '-')
                    return has_error;  /* no next argument or it is another option */
            }
            break;
        default:  /* invalid option */
            return has_error;
        }
    }
    *first = i;  /* no script name */
    return args;
}

/*
** Processes options 'e' and 'l', which involve running Lua code.
** Returns 0 if some code raises an error.
*/
static int runargs(lua_State *L, char **argv, int n)
{
    int i;
    for (i = 1; i < n; i++)
    {
        int option = argv[i][1];
        lua_assert(argv[i][0] == '-');  /* already checked */
        if (option == 'e' || option == 'l')
        {
            int status;
            const char *extra = argv[i] + 2;  /* both options need an argument */
            if (*extra == '\0') extra = argv[++i];
            lua_assert(extra != NULL);
            status = (option == 'e')
                     ? dostring(L, extra, "=(command line)")
                     : dolibrary(L, extra);
            if (status != LUA_OK) return 0;
        }
    }
    return 1;
}

static int handle_luainit(lua_State *L)
{
    const char *name = "=" LUA_INITVARVERSION;
    const char *init = getenv(name + 1);
    if (init == NULL)
    {
        name = "=" LUA_INIT_VAR;
        init = getenv(name + 1);  /* try alternative name */
    }
    if (init == NULL) return LUA_OK;
    else if (init[0] == '@')
        return dofile(L, init + 1);
    else
        return dostring(L, init, name);
}

/*
** Main body of stand-alone interpreter (to be called in protected mode).
** Reads the options and handles them all.
*/
static int pmain(lua_State *L)
{
    int argc = (int)lua_tointeger(L, 1);
    char **argv = (char **)lua_touserdata(L, 2);
    int script;
    int args = collectargs(argv, &script);
    luaL_checkversion(L);  /* check that interpreter has correct version */
    if (argv[0] && argv[0][0]) progname = argv[0];
    if (args == has_error)    /* bad arg? */
    {
        print_usage(argv[script]);  /* 'script' has index of bad arg. */
        return 0;
    }
    if (args & has_v)  /* option '-v'? */
        print_version();
    if (args & has_E)    /* option '-E'? */
    {
        lua_pushboolean(L, 1);  /* signal for libraries to ignore env. vars. */
        lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
    }
    luaL_openlibs(L);  /* open standard libraries */
    createargtable(L, argv, argc, script);  /* create table 'arg' */
    if (!(args & has_E))    /* no option '-E'? */
    {
        if (handle_luainit(L) != LUA_OK)  /* run LUA_INIT */
            return 0;  /* error running LUA_INIT */
    }
    if (!runargs(L, argv, script))  /* execute arguments -e and -l */
        return 0;  /* something failed */
    if (script < argc &&  /* execute main script (if there is one) */
            handle_script(L, argv + script) != LUA_OK)
        return 0;
    if (args & has_i)  /* -i option? */
        doREPL(L);  /* do read-eval-print loop */
    else if (script == argc && !(args & (has_e | has_v)))    /* no arguments? */
    {
        if (lua_stdin_is_tty())    /* running in interactive mode? */
        {
            print_version();
            doREPL(L);  /* do read-eval-print loop */
        }
        else dofile(L, NULL);  /* executes stdin as a file */
    }
    lua_pushboolean(L, 1);  /* signal no errors */
    return 1;
}

int lua_main(int argc, char **argv)
{
    int status, result;
    lua_State *L = luaL_newstate();  /* create state */
    if (L == NULL)
    {
        l_message(argv[0], "cannot create state: not enough memory");
        return EXIT_FAILURE;
    }
    lua_pushcfunction(L, &pmain);       /* to call 'pmain' in protected mode    */
    lua_pushinteger(L, argc);           /* 1st argument                         */
    lua_pushlightuserdata(L, argv);     /* 2nd argument                         */
    status = lua_pcall(L, 2, 1, 0);     /* do the call                          */
    result = lua_toboolean(L, -1);      /* get result                           */
    report(L, status);
    lua_close(L);
    return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}
